1. Technical Field
The present invention relates to a fryer assembly for the fabrication of snack food. More particularly, the invention relates to a form fryer assembly for the fabrication of snack food where product inlet and outlet conveyors replace a continuous lower conveyor, and further wherein product-centering elements disposed between individual mold segments keep frying product centered upon mold segments during frying.
2. Description of Related Art
Snack pieces are known to be prepared with the use of fryers. Generally, snack pieces such as fabricated potato crisps are formed from dough and are sheeted and cut into discrete pieces (pre-forms) for treatment. Treatment involves cooking the pre-forms in a fryer to produce cooked snack pieces. There are several types of prior art fryers typically used in the snack food industry for frying snack food products that require relatively even frying on all sides of the product. In general, these fryers cook product as it passes through in a stream of hot oil.
Particularly with potato crisps, a form fryer is beneficial because pre-forms can be molded and cooked into a desired product shape. A form fryer is a fryer for producing snack pieces having generally two conveyors, an upper and a lower conveyor. On each conveyor are molds or surfaces designed to interact with the opposing conveyor's molds or surfaces. After pre-forms are placed in the fryer, the top mold or contact surface keeps the now cooking pre-form beneath the surface of the oil until the fryer exit.
FIG. 1 shows an example of a prior art form fryer. The fryer assembly 10 has a fryer housing 12 that contains conveyors for moving pre-forms therethrough. To maintain desired environmental conditions within the housing 12, steam or inert gas may be circulated through portions above and around oil within the fryer and is supplied through a port 14, although additional ports may be added as needed. A top belt 20 is disposed in a top portion of the fryer housing 12 and is supported and rotated by two rollers 22, 24. A bottom belt 30 is disposed beneath the top belt 20. The bottom belt 30 is a continuous loop belt and is supported and rotated by two rollers 32, 34. A fryer pan 50 containing a body of oil 52 is situated within the fryer housing 12 so that at least a portion of the top and bottom belts 20, 30, when adjacent to each other, are passed through the oil 52. Oil 52 is circulated through a fryer pan 50 from an oil inlet 54 to an oil outlet 56 by, for example, a pump (not shown). Oil may be maintained at a desired cooking temperature with steam that is jacketed around the fryer pan 50.
For cooking, pre-forms are led towards the fryer by the bottom belt 30 starting at about the input-side roller 32. The pre-forms are then followed from above by the top belt 20 and led towards a point in the oil 52 where the bottom belt 30 comes into close proximity with the top belt 20. By at least this point, the pre-forms have made contact with at least one mold surface. While not depicted, molds are commonly placed on at least the exterior surface of the top belt 20 but may also be placed on the exterior surface of the bottom belt 30. Once the pre-forms are secured between the top and bottom belts 20, 30, which run substantially parallel to each other through the oil 52, they are introduced to the hot cooking oil 52 at an oil entry point 53. The pre-forms thereafter travel through the hot oil 52 in the oil pan 50 completely submerged until they emerge from the oil 52 at an oil exit point 55. A typical form fryer may be operated with an oil frying temperature between 240 to 400° F., although it is preferably operated between 320 to 380° F. Thereafter, the cooked snack pieces are transferred by the oil and conducted along the exit portion of the bottom belt 30 and are transferred to the next segment of the overall process at about the output-side roller 34 for seasoning, if desired, and packaging.
By using a form fryer such as the prior art example fryer assembly 10, snack foods, such as potato crisps, are capable of being fabricated with a standard and desirable shape. The frying of individual pieces presents numerous difficulties such as wrinkling, folding, clumping, and sticking to cooking surfaces. With the use of a form fryer, as opposed to other types of frying, a number of these difficulties can be resolved.
While form fryers resolve a significant number of problems in frying snack pieces, form fryers require a significant volume of oil. A large volume of equipment, along with the food product to be fried, must pass through hot oil and remain submerged for a time sufficient to cook the product. In traditional form fryers, there must be enough oil to submerge two conveyor belts, at least one product mold, and the product to be cooked. A considerable amount of energy, and thus money, is required to heat, pump and maintain this large volume of oil.
In addition, there is significant expenditure associated with replacing oxidized oil with fresh oil. Because form fryers typically have at least one conveyor with surfaces that cycle between the air and oil, the equipment itself introduces oxygen to the oil. Oil in the system gradually becomes oxidized as it absorbs oxygen at the air/oil interface and from submerging conveyor material. Oil oxidation causes oil to go rancid over time, thus the oxidized oil in the system must be replaced with fresh oil periodically. It would therefore be advantageous to reduce the volume of submerged equipment without adversely affecting the performance of the fryer. If the volume of submerged equipment can be reduced, the opportunity for such equipment to introduce oxygen into the oil can be reduced, thus slowing oxidation and reducing costs associated with replacing oxidized oil with fresh oil. In addition, expenditures for heating, pumping, and maintaining the oil can also be reduced.
A desirable feature of molded snack pieces is that they can be made uniform in size and shape. With uniformity, the snack pieces can be packaged in a seated alignment. This allows for the packaging of snack product into a canister as opposed to being packed loosely in a bag. Canister packaging provides a degree of protection against breakage of the snack pieces while providing improved transportability of the snack pieces both in bulk and in individual canisters. Also, canisters can be sealed with a lid after opening to deter product degradation.
For packaging of uniformly shaped product such as curved ellipses, (for example, an ellipse having its longer sides curved upward in the same direction) snack pieces are stacked first before filling in a canister. Snack pieces can be stacked one directly over another, or they can be partially overlapped in a similar manner as rooftop shingles are overlapped. After such overlapping, the product pieces are then pushed together so that each piece is directly over the other. While it is possible to stack curved product pieces either with concave sides up or concave sides down, the product pieces may be more amenable to stacking in one particular orientation, depending on the product shape.
For example, thin, elliptical product pieces having upwardly-curved sides are more easily stacked with their concave sides down rather than up. In the event that two adjacent product pieces fail to overlap, those pieces can only be forced to stack one over the other if their adjacent edges are at different heights. With their concave sides up, two adjacent elliptical product pieces cannot be restacked because their adjacent product edges would lie flat against the conveyor, and those edges would confront each other upon pushing the pieces together. With their concave sides down, however, the product pieces are able to rock back and forth on their downwardly curving edges in the direction of travel. This ability to rock makes it highly unlikely that the adjacent edges of two pieces would confront each other at the same vertical level. One product piece will thus be able to overlap and eventually stack over the other.
Conventional molds are convex and produce shaped snack pieces with concave sides facing upwards and away from the bottom belt. While the concave-side up orientation may be more suitable for seasoning, the concave-side down orientation, as previously explained, is often better for stacking. The product therefore must be flipped prior to packaging. If the cooked product left the fryer with concave sides facing down towards the fryer bottom belt, the product would not require flipping, albeit at the slight expense of seasoning efficiency.
Another problem encountered with prior art form fryers is the difficulty of providing a bottom conveyor that can accommodate the evolving shape of cooking product. As the product to be fried typically enters the fryer with one shape and exits with another, it is difficult to design a prior art bottom conveyor with product receptacles that can accommodate the shapes of both pre-forms and cooked product.
Still another problem encountered with prior art form fryers is the tendency of frying product pieces to shift from their desired positions or orientations against their respective mold surfaces. For example, when frying dough pieces up against a convex mold surface, the upward forces during frying can upset the centered placement of such dough pieces. The upward forces, often produced by evolving gas, can dislodge the dough pieces and cause them to shift to one side of the mold, which then results in deformed products. In extreme situations, dough pieces may even come to rest between or across adjacent mold surfaces.
Therefore, an improved form-frying device is desired. An improved form-frying device should eliminate the bottom conveyor and instead have separate bottom entrance and bottom exit conveyors, leaving a reduced volume segment between the two bottom conveyors. By eliminating the bottom conveyor in the reduced volume segment, less oil would be needed within the fryer system, and money can be saved on oil heating, pumping, maintenance, and replacement. Also, product should leave the improved form-frying device with an orientation appropriate for stacking, thereby eliminating the need for product flipping. By eliminating the product-flipping step, one can eliminate the cost of product-flipping machinery, as well as losses associated with product jam-ups in the flipping machinery. Furthermore, an improved form-frying device should have product-centering elements secured between individual mold surfaces to keep frying product pieces relatively centered against their respective mold surfaces.